Electrically heated coffee percolator

Abstract

An electric coffee percolator is provided with a fresh water container located above a water heating chamber sized to receive and retain about 30-60% of the volumetric amount of fresh water required for a complete coffee infusion. The heating chamber is separated by a common wall from the water container and receives fresh water therefrom through a non-return value located in the common wall. A ventilating pipe in the water container is slidably amounted in the common wall to project a selected distance into the heating chamber so that the water level in the heating chamber can be adjusted. A check valve in the ventilating tube prevents expulsion of water from the heating chamber into the water container. The bottom wall of the heating chamber is provided with an electric heating element surrounding a well from which a riser pipe through which the hot water is expelled extends upwardly to a water outlet chamber having a cross-sectional area which increase in size from its inlet end to its outlet end. The end of the riser disposed in the well is shaped to release steam pressure prior to the expulsion of the last bit of water remaining in the heating chamber to prevent the remainder of the water from being expelled at an excessive speed.

What is claimed is: 
     
       1. In an electrically heated coffee percolator of the type including a fresh water container, a heatable hot water chamber receiving water from said fresh water container through a non-return valve, and a riser pipe extending from said hot water chamber to a boiling water outlet, the improvement comprising said hot water chamber having a sufficient volumetric capacity to receive, through said nonreturn valve, and retain about 30 to 60% of the volumetric amount of fresh water required for a complete coffee infusion, said fresh water container being disposed immediately above said hot water chamber and a fresh water container bottom wall having said non-return valve located therein separating said hot water chamber from said fresh water container and serving as a common wall therebetween. 
     
     
       2. A coffee percolator according to claim 1, further comprising said riser pipe extending upwardly from a near end disposed in said hot water chamber, steam outlet opening means associated with said riser pipe and disposed at said near end and controlled by the water level in said hot water chamber for increasing the size of a steam outlet opening as the water level in the hot water chamber decreases, to prevent ejection of hot water with an excessive velocity due to steam pressure build-up. 
     
     
       3. A coffee percolator according to claim 2, wherein said steam outlet opening means comprises at least one steam outlet opening shaped and positioned to be progressively uncovered as the water level decreases. 
     
     
       4. A coffee percolator according to claim 3, wherein said steam outlet opening means comprises at least one of: a longitudinal slot along said riser pipe;   a plurality of openings located one above the other on said riser pipe;   an obliquely cut end portion of the riser pipe and;   a plurality of branch pipes projecting below said riser pipe and ending at different heights therebelow.   
     
     
       5. A coffee percolator according to claim 2, wherein said steam outlet opening means comprises at least one of: a longitudinal slot along said riser pipe;   a plurality of openings located one above the other on said riser pipe;   an obliquely cut end portion of the riser pipe and;   a plurality of branch pipes projecting below said riser pipe and ending at different heights therebelow.   
     
     
       6. A coffee percolator according to claim 1, wherein the end of said riser pipe remote from said hot water chamber opens into an outlet chamber having spaced inlet and outlet ends, the cross-sectional area of said outlet chamber measured perpendicular to a line connecting said ends at a point proximate said outlet opening being at least ten times the crosss-sectional area of said riser pipe. 
     
     
       7. A coffee percolator according to claim 6, wherein the outlet chamber is constructed so that its cross-sectional area increases in size from said inlet end to said outlet end. 
     
     
       8. A coffee percolator according to claim 6, wherein the interior or said outlet chamber is formed with ribs each extending substantially from said inlet end to said outlet end. 
     
     
       9. A coffee percolator according to claim 6, wherein said outlet end includes an opening formed at the lowermost point of a well in the bottom portion of said outlet chamber. 
     
     
       10. A coffee percolator according to claim 1, wherein said hot water chamber includes a bottom portion having a well-shaped configuration, said riser pipe having a near end located adjacent the lowermost point of said well. 
     
     
       11. A coffee percolator according to claim 10, further comprising heater means disposed in the bottom portion of said hot water chamber at a location spaced from the lower portion of said well. 
     
     
       12. A coffee percolator according to claim 1, further comprising means for adjusting the heat output of said heater means in accordance with the amount of coffee to be prepared, in such a manner that the percolation time may be kept constant at about 3 to 4 minutes, irrespective of the amount of coffee to be prepared. 
     
     
       13. In an electrically heated coffee percolator of the type including a fresh water container having a bottom wall, a heatable hot water chamber disposed below said water container and receiving water from said fresh water container through a non-return valve, and a riser pipe extending from said hot water chamber to a boiling water outlet, the improvement comprising said hot water chamber having a sufficient volumetric capacity to receive, through said non-return valve, and retain about 30 to 60% of the volumetric amount of fresh water required for a complete coffee infusion, a ventilating pipe slidably mounted in the bottom wall of said fresh water container so as to project downwardly into said hot water chamber, the extent of the downward projection of said ventilating pipe into said hot water chamber being thereby selectively adjustable, said ventilating pipe including a check valve for preventing the expulsion of water from said hot water chamber through said ventilating pipe, whereby the level to which said chamber is filled is controlled.